c# - 正则表达式替换和字符串不变性

Question

说我有一个编译的Regex对象：

    public static Regex myRgx = new Regex(@"[\d]+",RegexOptions.Compiled); 

Now let's say I'm reading large strings into the string variable SS , And then I use my Regex object to replace all matches within that string

    myRgx.Replace(SS,"($&)");

Question: Does .Replace internally use a StringBuilder to do the work , much like what happens in String.ReplaceAll() ?
And if it doesn't is there a way to get around this ?
Update :
I don't know if it's ok to ask another question as an update to the original question .. feel free to edit this out if it's not ok.
Question 2 : What if I need to preform a chain of replacements , Using multiple Regex objects, As in:

string input = "Some LARGE string";
input = rgx1.Replace(input,"substitution1");
input = rgx2.Replace(input,"substitution2");  
input = rgx3.Replace(input,"substitution3");  

我正在编写一个形态分析器，因此需要将正则表达式对象保持分开，并且替换必须按照上述代码中的特定顺序进行。正则表达式对象的数量很大，我们谈论的是千兆字节的文本，因此每次传递完一个正则表达式对象后，都要传递一个新的字符串对象，这实际上不是一个选择。
有什么建议么？

Answer 1

是的，Regex.Replace方法使用通过反射器发现的StringBuilder。